Adhesive materials including adhesives, tacky agent, sealant, coating agents, paints and the like are utilized in the industries ranging from civil engineering, architecture to packaging, bookbinding, automobile, electronics, fine chemicals, optics, carpentry, plywood, fabrics, leather as well as for domestic purposes, and their use has indeed become largely extensive. Applications of the adhesive materials include a variety of wood, metal, rubber, plastic, leather, ceramics and so forth, and recently concrete has been added to the above list.
These adhesives which are prepared in the form of a mixture of chemical substances which mainly uses synthetic resins generate toxic substances such as VOC (volatile organic compound), dioxin and endocrine disrupting chemicals due to an organic solvent used in preparing and the diverse volatile additives being added to improve properties. Recently the production and use of these toxic substances are strictly restricted by the international agreement on the environmental regulations. Furthermore, these regulations are used as a novel means of trade sanctions by EU and the like. To keep pace with the current, conventional solvent adhesives are gradually being replaced by those that are water-soluble, solvent-free and hot-melt.
Moreover, while most of the fine chemical materials as well as these adhesive materials are petrochemicals derived from oil refinery process, the global oil price is steadily increasing due to the decrease in its reserves and the surge in demand especially driven by BRICs. As the international agreement strictly regulating greenhouse gas emissions takes effect, it is expected that using irreversible fossil resources such as oil would take great toll on the environment.
Therefore, there are many efforts being made so as to obtain fine chemical products, from instead of oil resources, yet from novel resources onwards, the most typical source to use being carbohydrate-based biomass. [Ghheda, J. N.; Huber, G. W.; Dumesic, J. A. Angew. Chem. Int. Ed. 2007, 46, 7164-7183, Corina, A.; bona, S.; Velty, A. Chem. Rev. 2007, 107, 2411-2502.] A considerable amount of about 170 billion tons of carbohydrate are produced in nature through photosynthesis every year. Humankind however makes merely about 3% use of the total carbohydrate produced for food, paper, furniture, construction materials and so forth.
Consequently, the fine chemicals prepared from renewable and sustainable carbohydrate-based biomass are anticipated to be able to offer alternatives to the petrochemicals. More specifically, how to synthesize a compound containing some sort of adhesiveness or tackiness by using the carbohydrate-based biomass need be further studied in order to replace curable adhesive materials derived from conventional oil resources.
On the other hand, curable, particularly, photo-curable adhesive materials containing an acrylate-based or isocyanate-based functional group generally carry a rapid-curing property at a room temperature through a radical polymerization, wherein, however, lies a problem of causing large contraction due to the rapid curing rate. Due to the excessive contraction, the demand for introducing the materials with low contraction ratio after curing is currently present in the field where adhesive materials are used and especially in those of electronic materials and such where precise dimensional stability is required.